The present invention relates to an absorbent body intended for an absorbent article, such as a sanitary napkin or an incontinence guard, and comprising an absorbent material, such as cellulose fluff, which continuously increases in quantity from at least the side edges of said article in towards the centre thereof.
The most serious problem associated with the manufacture of sanitary napkins is one of producing a napkin which will not leak in use. The most common type of leakage is leakage from the sides of the napkin. Such leakage may have several causes. It may, for instance, be because the menstrual fluid disperses so poorly throughout the absorption body that the regions peripheral of the point of contact of the liquid with said body becomes quickly saturated, causing further liquid to flow beyond the edge margins of the towel. Another and more general reason is that the towel becomes distorted and squashed between the thighs of the wearer, so as to greatly reduce the area of the liquid-receiving surface of the towel. This latter problem is particularly manifest in modern sanitary towels, which are often made very narrow, so that the towel can be worn comfortably and discretely.
The Swedish Patent Specification No. 349 476 describes a sanitary towel or corresponding article, the absorbent body of which comprises fibrous absorbent material which varies gradually in quantity per unit of volume in the longitudinal and transverse directions of the towel.
The majority of this absorbent material is located in that part of the towel with which the liquid is first intended to come into contact, and the quantity of absorbent material contained in the body per unit of volume gradually decreases in a direction away from this region. In manufacture, this known absorption body has a thickness which is approximately the same over the whole area of the body, but which has latent expansion forces which are released when the towel is in use, such as to cause the centre part of the towel to expand. As a result of this expansion, the known towel adopts an ellipsoidal shape, which is said to be particularly desirable and to render the towel more comfortable when worn.
A significant drawback with this known sanitary towel is that the towel is soft and moldable and can therefore be squashed or likewise deformed in use, mainly in the transverse direction thereof, with a greater risk of leakage occurring in consequence thereof. Another serious drawback is that the sanitary towel swells in use, primarily in the direction of its thickness, thereby becoming less discrete when worn. It is found that the persons who use sanitary towels place great importance on the requirement that the towel is so discrete as to be unnoticeable when worn beneath everyday clothing. A discrete sanitary towel generally implies a towel which is thin. A thin or discrete towel is also considered by the majority of users to be more comfortable and pleasant to wear than a sanitary towel which is thick and bulky.